JOURNAL OF ENTOMOLOGICAL RESEARCH
Year:2011 | Volume:3 | Issue:3 (11)|Papers Count:8

The Corn Ground Beetle, Zabrus tenebrioides (Col., Carabidae) is an important cereal pest in Iran and some European countries. Serious damage leads to withering and drying of plants. In order to evaluate the potential of entomopathogenic fungi in control of this pest, field-collected adults were maintained under appropriate conditions and exposed to entomopathogenic fungi of genera, Beauveria, Metarhizium and Isaria, isolated from different hosts and geographical regions. The bioassay were carried out by submergence method with concentrations of 105, 106 and 107 conidia/ml of Tween 80® solution (0.05%) in three replicates and 10 insects in each replicate and exposure time of 60 sec. The results showed relatively low efficacy of these entomopathogenic fungi on the pest. ANOVA of mortalities proved significant differences among the isolates. DEMI 002 (an isolate of Metarhizium. anisopliae) showed the highest mortality (52.22%) than the other isolates. In case of DEMI 002, Values of LC50 (95% confidence intervals) and LT50 were obtained 7.21×106 (1.68×106, 6.76×109) and 13.37 days at 107 conidia/ml respectively.

The cabbage aphid, Brevicoryne brassicae (L). (Hom., Aphididae) is one of the most important pests of rapeseed and most other crucifer in many parts of the world In this study biological characteristics of B. brassica were conducted in laboratory conditions at temperature of 15, 20, 25 and 30oc, 60±5% relative humidity and photoperiod of 16: 8 hours (light dark). Researches biological characteristics of B. brassica showed that most of them disturbed at 30oc and they reached to minimum amount Longevity of adults and immature nymphal Stage at 15oc was significantly more than other three temperatures. Based on the results of this research, the lowest net reproduction rate (R0) of B. brassica was at 300 c (1.5) females per female per generation and highest at 25oc (1 47) females per female per generation. The intrinsic rate of increase (rm) at 15oc, 20oc, 25oc and 30oc were 0.144, 0.2498, 0.317, 0.037 females per female per day respectively According to result, optimum temperature for development of Brevicoryne brassicae was 25oc and can raise their population rapidly.

Greenbug, Schizaphis graminum (Rondani) is one of the injurious pests of grain sorghum in Iran. In this study, the effect of six grain sorghum cultivars on biological characteristics of greenbug was investigated in a greenhouse at 25±2oC and 60-70% RH. The experiment was carried out by rearing aphids on leaves of six common grain sorghum varieties including: KGS17 KGS19, KGS20, Payam, Sepideh and Kimia using leaf cages. Nymphal development time, mortality, longevity, preoviposition, oviposition and postoviposition periods and fecundity of the aphid were recorded daily. Results revealed that nymphal survival rate of the aphid was very high (87-98%) on all studied cultivars like that on sensitive host plant cultivars. The aphid had relatively high longevity (29.1±1.58-33.3±1.09 days) and short nymphal development time (5.85-6.35 days) on studied sorghum cultivars. The highest longevity was observed on KGS17, but sorghum cultivars had not significant effect on the aphid longevity. The lowest and the highest aphid fecundity was obtained on KGS19 (29.85±3.34 nymphs) and KGS20 (44.95±2.69 nymphs) cultivars, respectively. Fecundity of the aphid was higher on KGS20 than KGS17, KGS19 and Payam cultivars, significantly. Based on the results, the highest nymphal mortality was observed on the KGS19 cultivar. Besides, rearing S. graminum on this cultivar increased nymphal development time and reduced aphid fecundity, significantly. Consequently, KGS19 was less suitable to greenbug than other studied cultivars.

The leaf miner Agromyza sp. is one of the most important pests of chickpea. Seasonal fluctuation of percent parasitism of the pest was investigated on chickpea in Khomeyn-Iran in 2009. Samples were taken on two days a week and number of larvae and parasitized larvae per plant was counted and were transferred to laboratory. The parasitoids emerged from larvae were identified in Tabriz by Dr. Lotfalizadeh. The highest percent was 18.8 on 29 June. In this experiment the parasitoids activity and the peak of leaf miners larvae population were in the same time in khomeyn region. In probability level 0.05, the correlation between leaf miners larvae and % parasitism was positive and significant (R2=0.6) and it decades when there is increasing in larvae population, there is increasing in % parasitism too.

One of the most promising alternatives to synthetic insecticides for the control of stored product pests is diatomaceous earth (DE). Laboratory studies were performed to evaluate the insecticidal effects of Iranian formulation of DE (Sayan®) on adults of bruchid beetle, Callosobracus maculatus F. (Coleoptera: Bruchidae), at 30±1oC and 60±5% RH in dark. Experiments for bioassay and adult emergence evaluation, were carried out with 5 concentrations (30, 72, 173 and 416 ppm (mg DE/kg wheat)) and 6 concentrations (0, 30, 72, 173, 416 and 1000 ppm), respectively, with 6 replications. The results showed that the concentration 416 ppm of DE had acceptable effects on C. maculatus mortality after 3 days. After 3 days, the LC50 of DE for C. maculatus adults was estimated to be 58.85 ppm. There was significant difference between DEtreated and untreated bean for progeny production, as DE killed the newly emerged beetles and the concentration 1000 ppm of DE had acceptable effects on F1 emergence reduction (81%). As time goes by, DE stability and efficiency were constant. As a result, Iranian formulation of diatomaceous earth (Sayan®) can be used to protect grains against C. maculatus adults.

The predaceous mites of the family Phytoseiidae were collected on different plants in Ilam Province during two years (2007-2008). The mites were separated by placing plant materials into a Berlese funnel or by examining under the dissecting microscope. The collecting mites were cleared in Nesbitt s fluid and mounted in Hoyer s medium on microscope slides. Twelve species belonging to three subfamilies Phytoseiinae, Typhlodrominae, Amblyseiinae and six genera were collected and identified. All species are reported for the first time from Ilam Province. The list of identified species is as follow:Subfamily PhytoseiinaePhytoseius plumifer (Canestrini and Fanzago, 1876)Phytoseius ciliatus Wainstein, 1975Subfamily TyphlodrominaeParaseiulus talbii (Athias Henriot, 1960)Paraseiulus soleiger (Ribaga, 1904)Typhlodromus (Anthosius) persianus McMurtry, 1977Typhlodromus (Anthosius) bagdasarjani Wainstein and Arutunjan, 1967Subfamily AmblyseiinaeEuseius scutalis (Athias- Henriot, 1958)Euseius finlandicus (Oudemans, 1915)Kampimodromus aberrans (Oudemans, 1930)Neoseiolus barkeri Hughes, 1948Neoseiulus marginatus (Wainstein, 1961)Neoseiulus bicaudus (Wainstein, 1962)

The pathogenicity of four isolates of Beauveria bassiana fungus including DEBI 015, DEDI 002, DEDI 001 and DEBI 004 were studied on adults of Aphis gossypii. Concentrations of 102, 103, 104, 105 and 106 spores /ml. applied on aphids and LC50 for each isolate was calculated. Results showed that the DEBI 015 isolate had the highest toxicity (lowest LC50) with 13.5 spores/ml. and the DEBI 004 isolate had the lowest toxicity (highest LC50) with 269538 spores/ml. Lethal time (LT50) for all isolates was calculated only for three doses of 104, 105 and 106 spores/ml. The longest mortality time belonged to DEBI 004 isolate with 106 spores/ml. in 5.66 days and the shortest belonged to DEBI 015 isolate with 106 spores/ml. in 3.32 days. It is concluded that in all test concentrations, the DEBI 015 isolate had the highest rate of mortality in 1-106 spores/ml. with mortality range of 33.5- 96.7%.

The larvae of the Sawtoothed beetle are attacked by the ecto-parasitoid, Cephalonomia tarsalis, and the entomophagous fungi, Beauveria bassiana in natural habitats. Interaction of simultaneous activities of the both natural enemies may affect the efficiency and predation behavior of the parasitoid in regulating the pest population. Therefore, the two important behaviors of the parasitoid, the functional response and host preference, were studied under laboratory conditions. For this purpose, the infested and non-infested pest larvae were used in separate and mixed conditions. Type III Holling’s model was fitted on data obtained for infested or non-infested larvae of the Sawtoothed beetle. The parasitoid preferred the non-infested larvae. The functional response in condition of using the mixed pest larvae, showed an inverse trend of parasitism. An equal number of larvae from both groups were parasitized when the number of infested larvae was 1.5 times of non-infested ones. In higher proportions of infested larvae, the parasitism increased in favor of infested larvae. In all conditions, the wasp did not reject the infested larvae absolutely. It is concluded that there is a competitive relationship between the wasp and the fungus and this is a promising future for using the both in biological control of the Sawtoothed beetle in IPM programs.